As the design rules of semiconductor devices change, it has become increasingly necessary to form deeper, narrower contacts with higher aspect ratios. The formation of a deep, narrow contact with a high aspect ratio involves an etching or cleaning step. When treating a wafer on which a high aspect ratio structure is formed by etching, cleaning, or drying the wafer, defects may frequently occur due to damage to other layers of the wafer and/or water spots on a wafer surface when a conventional wet etching process is utilized. Furthermore, when a wet etching process is performed to remove a mold oxide layer, which is used as a sacrificial layer when forming a storage node for a capacitor, the storage node of the capacitor tends to lean or collapse after the removal of the mold oxide layer due to the high surface tension of pure water.
To solve the above-mentioned problems, etching, cleaning, and/or drying a predetermined layer on a wafer using a supercritical CO2 solvent have been proposed. Unfortunately, conventional methods for treating wafers using supercritical CO2 solvent may allow only one wafer to be treated at a time in order to maintain a high temperature, a high pressure supercritical state. As such, the use of supercritical CO2 processing may cause reduced process throughput.